Effects of vitamin A deficiency on the inter-Sertoli cell tight junctions and on the germ cell population.

When 20-day-old rats are placed on a vitamin A deficient diet (VAD) for a period of 10 weeks, the seminiferous tubules are found to contain only Sertoli cells, a few residual A0, A1 spermatogonia, and preleptotene spermatocytes (PL). The type A1 spermatogonia and PL spermatocytes are arrested in their G2 phase. In VAD rats type A2-A4, intermediate (In) and B spermatogonia and all types of spermatocytes (except PL spermatocytes) and spermatids are eliminated from the seminiferous tubules. Two questions were raised in this investigation: 1) Is there, in VAD rats, any correlation between a breakdown of the blood-testis barrier (e.g., Sertoli cell tight junctions) and germ cell loss? 2) Is the disappearance of most germinal cells due to their degeneration during spermatogenesis or to a maturation depletion process resulting from an arrest of spermatogenesis at the spermatogonial stage? To investigate these questions four groups of male Sprague-Dawley rats (20-days old) were fed a VAD diet for 7 to 12 weeks. The testes were fixed by perfusion with 2.5% glutaraldehyde in 0.1 M sodium cacodylate containing 2% lanthanum nitrate, an electron opaque tracer used to test the patency of Sertoli cell tight junctions. The lanthanum permeated the intercellular space of the basal compartment but was arrested by normal inter-Sertoli cell tight junctions. The seminiferous epithelium showed numerous degenerating germ cells, some being internalized by Sertoli cells as membrane-bound phagosomes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ultrastructure of the seminiferous epithelium and intertubular tissue of the human testis

The ultrastructural features of the human testis are reviewed with emphasis upon the process of spermatogenesis and the cytology of the Leydig cells. The seminiferous epithelium is structurally partitioned by the Sertoli cells into basal and adluminal compartments via the specialized tight junctions between the Sertoli cells. Spermatogonia reside in the basal compartment, and, via a series of cell divisions, produce the primary spermatocytes, which at the commencement of their development move into the adluminal compartment, and thus the lengthy process of meiotic maturation is initiated. The fine structure of primary spermatocytes is described together with the complex transformation of the spermatids into spermatozoa during the process of spermiogenesis. Earlier studies of the organization of the human seminiferous epithelium showed that germ cells at different developmental stages formed identifiable collections termed cell associations or stages, but since several stages were seen in a single tubule cross-section, this gave the impression of an extremely irregular pattern of spermatogenic development. When the topographic arrangement of germ cells was re-examined with the aid of computer modelling, a highly ordered distribution was revealed, conforming to a helical pattern based on the geometry of spirals. Thus spermatogenesis in the human testis is subjected to a precise regulation in keeping with the ordered arrangement of the germ cells seen in other mammalian species. The intertubular tissue of the human testis is composed of loose connective tissue containing blood vessels, occasional lymph capillaries, macro-phages, mast cells, and the Leydig cells which occur either as single cells or form small clusters. The Leydig cell cytoplasm contains an abundant supply of smooth endoplasmic reticulum and mitochondria with tubular cristae, both features being characteristic of steroidogenic cells. Human Leydig cells contain large Reinke crystalloids of variable size and number, but their function remains obscure. The frequent occurrence of paracrystalline inclusions within the cytoplasm of the human Leydig cell suggests that these elements are precursors of the Reinke crystalloids.     

Morphologic and morphometric analysis of testis of Pseudis limellum (Cope, 1862) (Anura, Hylidae) during the reproductive cycle in the Pantanal, Brazil

The spermatogenesis of Pseudis limellum, from the Southern Pantanal, Brazil, was studied from July 1995 to May 1996, through histological sections of the testis. The cells could be differentiated as: primary spermatogonia, large cells, generally with bilobed nucleus; secondary spermatogonia, smaller cells, with darker cytoplasm, chromatin of radial form; primary and secondary spermatocytes, differentiated according to the different stages of the nucleus during the successive cells divisions. Furthermore, we observed cells in process of morphologic differentiation: rounded spermatids much smaller, with nucleus containing chromatin in compacting process and cytoplasm reduction; elongated spermatids, generally parallel organized in well defined bundles, with the anterior region directed toward the periphery of the seminiferous tubule and the tail directed toward the lumen. Spermatozoa are free in the lumen of the seminiferous tubule. All the cells are organized as cysts, which are supported by a large amount of Sertoli cells. The spermatogenesis in P. limellum is very similar to that of other anurans, but peculiarities were observed regarding the organization of the germ cells, the great amount of free Sertoli cells in the lumen of testis collected in May, and the long cytoplasmatic extensions of the cells bearing pigments and involving the seminiferous tubule. The diameter of the seminiferous tubule (SD) exhibited an annual mean of 251.79 +/- 37.57 microm. Spermatozoa number by seminiferous tubule (SN) exhibited an annual mean of 306.66 +/- 39.83, also with higher and lower values at each month. Variations in SD and SN were not significantly correlated with climatic variables. In this species, reproduction occurs throughout the year in ponds and flooded areas, despite the seasonal climate of the Pantanal. Although males varied in their annual reproductive activity, they were considered potentially reproductive in all months throughout the year.     

Cellular architecture of the testis of Egyptian wild boar (Sus scrofa) in young and adult age

Testicular parenchyma is split into lobules, each lobule contains convoluted seminiferous tubules surrounded by myoid cells and the interstitial tissue contains groups of Leydig cells. The seminiferous tubules are lined by two groups of cells the first one is the spermatogenic cells and the second one is Sertoli cells.     

The blood-testis barrier and Sertoli cell junctions: structural considerations.

In this review, a few well-established axioms have been challenged while others were viewed from a new perspective. The extensive literature on the blood-testis barrier has been scrutinized to help probe its mechanics and hopefully to promote understanding of the constant adaptation of the barrier function to germ cell development. Our principal conclusions are as follows: (1) Although the barrier zonule is topographically located at the base of the seminiferous epithelium it actually encircles the apex of the Sertoli cell. Consequently the long irregular processes specialized in holding and shaping the developing germ cells should be considered as apical appendages analogous to microvilli. (2) The development of the barrier zonule does not coincide with the appearance of a particular class of germ cells. (3) The barrier compartmentalizes the epithelium into only two cellular compartments: basal and lumenal. (4) Although the blood-testis barrier does sequester germ cells usually considered antigenic, immunoregulator factors other than the physical barrier seem to be involved in preventing autoimmune orchitis. (5) Structurally, a Sertoli cell junctional complex is composed of occluding, gap, close, and adhering junctions. The Sertoli cell membrane segments facing germ cells are presumably included in the continuum of the Sertoli cell junctional complex that extends all over the lateral and apical Sertoli cell membranes. (6) The modulation (i.e., formation and dismantling) of the junctions in a baso-apical direction is characteristic of the seminiferous epithelium and may be dictated by germ cell differentiation. The formation of tubulobulbar complexes and the following internalization of junction vesicles conceivably represent sequential steps of a single intricate junction elimination process that involves junction membrane segments from different cell types as part of a continual cell membrane recycling system. (7) The preferential association of junctional particles with one or the other fracture-face reflect a response to various stimuli including seasonal breeding. Changes in the affinity of the particles are generally coincidental with cytoskeletal changes. However, changes in the cytoskeleton are not necessarily accompanied by permeability changes. The number of strands seems to reflect neither the junctional permeability nor the transepithelial resistance. The diverse orientation of the strands seems to be related to the plasticity of the Sertoli cell occluding zonule. (8) Cooperation between all constituents (Sertoli cells, myoid cells, cell substratum, and germ cells) of the epithelium seems essential for the barrier zonule to function in synchrony with the germ cell differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)     

The actin filament network associated to Sertoli cell ectoplasmic specializations

Junctional devices in Sertoli cells conform the blood-testis barrier and play a key role in maturation and differentiation of germ cells. The spacial distribution of ectoplasmic specializations of Sertoli cells was studied by beta-actin immunolabelling, using laser confocal and transmission electron microscopy. For confocal microscopy, beta-actin immunolabelling of ectoplasmic specializations was studied over the background of either prosaposin or glutaredoxin immunolabelling of the Sertoli cytoplasm. Labelling was found near the basal lamina, surrounding early spermatocytes (presumably in leptotene-zygotene) or at one of two levels in the seminiferous epithelium: (1) around deep infoldings of the Sertoli cell cytoplasm, in tubular stages before spermiation, and (2) in the superficial part of the seminiferous epithelium, in tubular stages after or during spermiation. For transmission electron microscopy, beta-actin immunolabelling of ectoplasmic specializations was also used. Ectoplasmic specializations were found at two different levels of the seminiferous epithelium. We also used freeze fracture to analyze the characteristics of tubulo-bulbar complexes, a known component of apical ectoplasmic specializations. Also, these different approaches allowed us to study the complex arrangement of the actin cytoskeleton of Sertoli cells branches, which surround germ cells in different stages of the spermatogenic cycle. Our results show a consistent labelling for beta-actin before, during and after the release of spermatozoa in the tubular lumen (spermiation) suggesting a significant role of the actin network in spermatic cell differentiation. In conclusion, significant interrelations among the beta-actin network, the junctional complexes of the blood-testis barrier and the ectoplasmic specializations were detected at different stages of the seminiferous cycle.     

The peptide fraction of <i>Bothrops jararaca</i> snake venom induces toxicological effects on the male reproductive system after local envenomation in mice

Bothrops envenomation is complex and provokes prominent local tissue damage and systemic disturbances, but little is known about their effects on the male reproductive system. After intratesticular injection, the bioactive peptide fraction (Bj-PF) obtained from Bothrops jararaca snake venom changes the structure of different stages of the seminiferous epithelium cycle in adult mice. For the first time, we investigated whether local envenomation of Bj-PF induces toxicological effects on the male reproductive system, particularly on the seminiferous epithelium and Sertoli cells. Male adult mice were treated with 0.24 mg.kg⁻¹ by intramuscular (i.m.) injection for 24 h. The testes samples were collected for morphological and morphometric evaluation. The toxicological effects of Bj-PF were also analyzed on mitochondrial metabolism and nitrite (NO₂) production in 15P-1 Sertoli cell culture. Bj-PF changed the structure and function of the seminiferous epithelium, particularly the disruption of the epithelium and the presence of degenerated germ cells in the adluminal compartment, but there were no alterations in the basal compartment. Bj-PF increased the thickness of the seminiferous epithelium and decreased the lumen diameter of the tubule. Semiquantitative histological assessment of the degree of tubule degeneration revealed that Bj-PF also increased the number of hypospermatogenic tubules compared to control. Bj-PF reduced NO₂ levels in 15P-1 Sertoli cells without changing the mitochondrial metabolism. Overall, the fact that Bj-PF alters the structure and function of the seminiferous epithelium suggests that bioactive peptides found in B. jararaca snake venom can have toxicological effects on the reproductive systems of affected male mice, providing new insight into the biological characteristics of snake venom and therapeutic strategies for envenomation inflammation.     

Characterization of Sertoli cell perinuclear filaments.

Sertoli cell nuclei are characterized by deep invaginations and, in addition, the orientation of the nuclei with respect to the wall of the seminiferous tubules varies during the cycle of the seminiferous epithelium. These events may be the result of cytoplasmic filaments acting at the level of the nuclear capsule and may represent significant changes in Sertoli cell activity. Thus, a study was performed to characterize the nature of the perinuclear filaments of Sertoli cells in vivo and in vitro. In Sertoli cells in vivo, microtubules and microfilaments were often detected in the perinuclear cytoplasm, and these cytoskeletal components were observed to course either parallel to, or abut at, the nuclear capsule. In Sertoli cells in vitro, the nuclear infoldings are retained and the perinuclear cytoskeleton was shown to contain microtubules, f-actin, and intermediate filaments. A fixation-permeabilization protocol employing tannic acid-saponin was used and it significantly enhanced the preservation of cytoskeletal components. The presence of f-actin was demonstrated by using the S1 fragment of muscle myosin to decorate the microfilaments. Treatment of the cultured cells with either microtubule or f-actin depolymerizing agents had no effect on nuclear shape. Thus, at present, the function of the prominent perinuclear cytoskeletal components remains unknown.     

Nickel nitrate: a new junction permeability tracer for the study of the blood-testis barrier.

With the purpose of evaluating a new intercellular tracer, nickel-K ferrocyanide, we compared results yielded by lanthanum with information provided by nickel. This was done in the seminiferous epithelium of Holtzman rats of several postnatal ages and in a wild local seasonal breeder Galea musteloides. Tissues were studied with transmission electron microscopy and freeze-fracture replications. Nickel tracing proved to delineate cell contours more intensely and less interruptedly than lanthanum. With regard to seasonal variations in adult galea, the limits of the barrier were similar to those described in other mammals: spermatogonia, preleptotene, and leptotene spermatocytes were surrounded by the tracer in the basal compartment. The zygotenepachytenes were contained in the lumenal compartment and tracers were stopped at the inter-Sertoli cell tight junctions. During the inactive spermatogenic phase in winter, the seminiferous epithelium contained Sertoli cells and occasional germ cells, never beyond the spermatocyte stage. The tracer filled intercellular spaces, indicating that the barrier was incompetent. Some resting germ cells showed nuclear hyperchromasia, karyolysis, organelle loss, cell shrinkage, and cell fusion leading to a multinucleated cells. The inter-Sertoli tight junctions were scanty and had randomly oriented and discontinuous junctional strands. Moreover, inter-Sertoli cell gap junctions proliferated. During the active spermatogenic phase in summer, junctions were numerous. Their junctional strands were parallel to each other, and continuous.     

Role of HSP70 in the regulation of the testicular apoptosis in a seasonal breeding teleost Prochilodus argenteus from the São Francisco river,Brazil

This study investigated the relationship among heat shock protein 70 (HSP70), proliferating cell nuclear antigen (PCNA), and testicular apoptosis during a breeding cycle of Prochilodus argenteus, a neotropical migratory characiform fish of importance in commercial fishery from the São Francisco River basin. A total of 48 (12 fish/sampling) adult males were caught using casting and drifting nets in four samplings from June 2008 to March 2009. Immunohistochemistry, Western blotting, terminal transferase‐mediated dUTP nick‐end labeling (TUNEL), enzyme‐linked immunosorbent assay (ELISA), and caspase‐3 colorimetric assay were assessed in different phases of spermatogenesis. Labeling for HSP70 occurred in spermatogonia (SPG_A 18.0±1.5 and SPG_B 27.9±1.0 in 100 mm², respectively) and Sertoli cells in all sampling periods, with higher values in June (resting period) while spermatocytes were labeled in September (maturation period) and December (ripe period). For PCNA, immunoreaction was predominant in spermatogonia in June and September, while primary spermatocytes were labeled mainly in December (18.7±2.0). TUNEL‐positive reaction occurred throughout the sampling periods, and labeling was detected in the nucleus of germ cells in all developmental phases, except spermatozoa. By ELISA, total HSP70 in testis increased significantly from June to December, and decreased in March (regression period), P<0.05. Caspase‐3 activity decreased from June to December and increased in March. Taken together, our results suggest that HSP70 may protect the germ cells from caspase‐3‐dependent apoptosis during testicular activity and, reduction of HSP70 and increase of apoptosis contribute for testicular remodeling after the breeding season in wild populations of P. argenteus in the São Francisco River. Microsc. Res. Tech. 76:350–356, 2013. © 2013 Wiley Periodicals, Inc.     

Effect of a 2-month light cycle regimen on testicular parameters of adult Ile-de-France rams.

This experiment was conducted in Ile-de-France adult rams to examine the target point of a 2-month light cycle regimen on seminiferous tubule functions, on intertubular compartment and on Leydig cell parameters. Eight rams were subjected to a 2-month light cycle regimen and were compared to sexually active or inactive rams. In light-treated rams, testis weight was maintained equal or was higher than that of sexually active rams. Both tubular and intertubular tissues were found significantly higher in light-treated than in sexually active rams. The mean ratio of basement membrane area of the seminiferous tubules per Sertoli cells and the daily productions of A1 spermatogonia and of leptotene primary spermatocytes were significantly increased in light-treated rams as compared with sexually active or inactive rams. Meanwhile, the dairy productions of diplotene primary spermatocytes, of round spermatids, of spermatozoa and of the rete testis fluid were not significantly increased in light-treated as compared with sexually active rams but significantly greater than those of sexually inactive rams. Total volume, total numbers, and individual volumes of Leydig cells were at least equal or higher in light-treated than in sexually active rams.     

Ultrastructure of the ovariole sheath in <i>Diatraea saccharalis</i> (Lepidoptera: Pyralidae)

The ultrastructure of the ovariole sheath along the Diatraea saccharalis ovariole was studied by scanning and transmission electron microscopy. Each ovariole is surrounded by an epithelial sheath, a tunica propria and scattered lumen cells. These three components of the ovariole sheath show different ultrastructural features along the ovariole, in the germarium or in the vitellarium; these differences are more evident in the epithelial sheath cells. The epithelial sheath is composed by two layers of cells, the external one running longitudinally and the internal one running circularly in the ovariole. These cells, in vitellarium, present cytoplasmic bundles of myofilaments that are arranged parallel to the long axis of the cells; these myofilaments are apparently related to the contraction movements of the follicles within the ovariole. The acellular tunica propria, composed of finely filamentous material, is attached to the adjacent follicle cells by adhesive dense plates. Between the epithelial sheath and the tunica propria there is a population of lumen cells, with morphological features of secretory activity     

Immunogold electron microscopic localization of antigenic sites in the outer dense fiber region of rat sperm tail obtained by using antisera to two Sertoli cell secretory proteins

Polyclonal antisera raised against polypeptide components of two rat Sertoli cell secretory proteins, designated protein S70 and S45–S35 heterodimeric protein on the basis of cell origin and estimated molecular weight, were used to identify antigenic sites in (1) rat testis, () cultured Sertoli cells, (3) developing spermatids (collected from spermatogenic stage-specific seminiferous tubular segments), and (4) epididymal sperm. Indirect immunofluorescence, immunoper-oxidase, and immunogold electron microscopy (single and double labeling) were used. Immunocytochemical techniques have detected antigenic sites in (1) the cytoplasm of Sertoli cells in the intact seminiferous tubule and in culture in the form of a punctuate, granular-like pattern, and (2) the acrosome (but not the Golgi region) and tail of developing spermatids and sperm. In developing spermatids, the principal piece of the tail displays a characteristic apical-to-distal immunoreactive banding pattern that correlates both temporally and spatially with the reported multistep assembly of outer dense fibers along the axoneme. The immunoreactivity of the acrosome, connecting piece, and outer dense fibers of the sperm tail was confirmed by immunogold electron microscopy. A precise identification of the component(s) of the outer dense fiber region responsible for the antigenic homology with Sertoli cell secretory proteins is under investigation.     

Aberrant distribution of junctional complex components in retinoic acid receptor alpha‐deficient mice

Retinoic acid receptor alpha (RARα)‐deficient mice are sterile, with abnormalities in the progression of spermatogenesis and spermiogenesis. In this study, we investigated whether defective retinoid signaling involved at least in part, disrupted cell–cell interactions. Hypertonic fixation approaches revealed defects in the integrity of the Sertoli‐cell barrier in the tubules of RARα‐deficient testes. Dye transfer experiments further revealed that coupling between cells from the basal to adluminal compartments was aberrant. There were also differences in the expression of several known retinoic acid (RA)‐responsive genes encoding structural components of tight junctions and gap junctions. Immunostaining demonstrated a delay in the incorporation of zonula occludens (ZO‐1), a peripheral component protein of tight junctions, into the Sertoli cell tight junctions. Markedly reduced expression of connexin‐40 in mutant pachytene spermatocytes and round spermatids was found by in situ hybridization. An ectopic distribution of vimentin and disrupted cyclic expression of vimentin, which is usually tightly regulated during spermiogenesis, was found in RARα‐deficient testes at all ages examined. Thus, the specific defects in spermiogenesis in RARα‐deficient testes may correlate with a disrupted cyclic expression of RA‐responsive structural components, including vimentin, a downregulation of connexin‐40 in spermatogenic cells, and delayed assembly of ZO‐1 into Sertoli cell tight junctions. Interestingly, bioinformatic analysis revealed that many genes that are components of tight junctions and gap junctions contained potential retinoic acid response element binding sites. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.     

The histomorphological structure of the male reproductive system of maize leaf weevil Tanymecus dilaticollis Gyllenhal, 1834 (Coleoptera: Curculionidae)

The histomorphology of the reproductive system and the germ cells has been useful to establish phylogenetic relationships in many insects. However, these elements remain little known in the Curculionidae. In this study, histomorphological structure of the male reproductive system of Tanymecus dilaticollis, which is economically important, is described, illustrated using stereomicroscopy, light microscopy, and scanning electron microscopy techniques, and discussed in relation to other Coleoptera species. Results showed that distinctive features of the male reproductive system of T. dilaticollis consist of a pair of yellowish testes, a pair of seminal vesicles, a pair of vasa deferentia, an ejaculatory duct, accessory glands, prostate glands, and aedeagus. Each testis is subdivided into two testicular follicles, enclosed by a peritoneal sheath. Each follicle of the mature testes is full sperm cysts with germ cells at various stages development of spermatogenesis. The testes have four types of germ cells (spermatogonia, spermatocytes, spermatids, and spermatozoa). They are occupied by the growth zone containing spermatogonia and spermatocytes, the maturation zone containing spermatids, while differentiation zone containing spermatozoa. There is a seminal vesicle at the center of each testis. Most mature sperms are stored in the seminal vesicle. Each testis is attached to the vas deferens by a stalk‐like seminal vesicle. In the distal part, vasa deferentia fuse with the ejaculatory duct. It is linked to the aedeagus. The provided results will contribute to the understanding of the reproductive cell biology of Curculionidae.     

Seasonal testicular changes in <i>Dendropsophus minutus</i> Peters, 1872 (Anura,Hylidae)

The reproductive cycle in anurans may be either continuous or discontinuous. These differences may be connected to seasonal climate changes and/or to anthropic activity. Forty adult male individuals of the Dendropsophus minutus species were collected during one year, in the municipality of Chapada dos Guimarães (Mato Grosso, Brazil). The testicles were studied under light and transmission electron microscopy. No variations were observed when the diameter of the seminiferous tubules and the thickness of the interstitial tissue were studied. However, changes in spermatogenesis were conspicuous and indicated that the reproductive cycle of D. minutus in Chapada dos Guimarães is discontinuous and seems related to variations in air temperature and rainfall.     

Role of resistance physical exercise in preventing testicular damage caused by chronic ethanol consumption in UChB rats

Ethanol consumption is associated with spermatogenesis damage and testosterone level alterations. Alcohol remains the most commonly used substance among athletes and sports enthusiasts. This study evaluated whether resistance physical exercise can reduce the testicular damage caused by ethanol exposure. A total of 36 ethanol drinking (UChB) rats were divided into four groups: C (control rats), ETOH (ethanol consumption), ETOH + T (ethanol consumption + physical training), and T (group physical training). The physical training component of the T and ETOH + T groups was based on a resistance training model consisting of four sets of 10 jumps, with an increasing overload of 50–70% of the body weight attached to the chest three times per week. Rats in the ETOH and ETOH +T groups received 10% ethanol. At postnatal day 90, the rats were sacrificed. Blood sample was collected for hormonal analysis, and the testicles were weighed and processed for histopathological, morphometric, and immunohistochemical analyses. The ETOH group showed an increase in testosterone levels. The immunohistochemical of androgen receptor and the absolute weight of the testes were higher in the ETOH and ETOH + T groups, while the ETOH animals showed a decreased weight gain index. The number of abnormal seminiferous tubules increased in the ETOH and T groups compared to those in the control group (C); however, the association with treatment (ETOH + T group) prevented this effect and decreased caspase‐3 production. In conclusion, these findings show that the combination of ethanol consumption and resistance physical exercise can prevent testicular damage in adult UChB rats.     

High-Resolution scanning electron micrographs of freeze-cracked cells in testes from normal and irradiated rats at different stages of gonadal development

Newly developed techniques in high-resolution scanning electron microscopy (SEM) and for tissue-processing procedures have been applied to an investigation of structures of various cells in rat testes at different stages of gonadal maturation. A series of high-resolution SEM micrographs are presented which survey the surfaces of different types of testis cells during normal development, and which also illustrate ultrastructural features of some of their intracellular organelles. In addition, a series of high-resolution SEM micrographs are presented which compare the structural features of Sertoli cells in normal testes with those in germ-cell-depleted testes obtained from rats killed at varying times after having been irradiated in utero. We describe our observations on the structural properties of surfaces and intracellular organelles in Sertoli cells, Leydig cells, peritubular myoid cells, and some classes of germinal cells. We also consider the possible role of Sertoli cell apical cytoplasmic processes in lumen formation. Similarities are pointed out between the structure of germ-cell-depleted testes, resulting from irradiation in utero, and the structure of germ-cell-depleted testes in seasonal breeders during periods of involution. Finally, we discuss advantages and disadvantages of methods employed to reveal the fine structure of intracellular organelles in cells of the testis.     

Localizations of intracellular calcium and Ca2+-ATPase in hamster spermatogenic cells and spermatozoa

Calcium plays a predominant role regulating many functional processes of spermatogenesis and fertilization. The purpose of the present study is to define the exact location of calcium as well as examine the role it plays during spermatogenesis and sperm capacitation. Testes and epididymides were obtained from adult healthy male hamsters. Spermatozoa were incubated with modified Tyrode's medium up to 4 h at 37 degrees Celsius for sperm capacitation in vitro. Samples of the testes and sperm cells were analyzed by cytochemical techniques to determine the location of calcium and Ca(2+)-ATPase and the percentage of acrosome reactions under light and electron microscopy. The data showed that (1) Sertoli cells exhibited numerous calcium precipitates as large, round, electron-dense bodies distributed throughout the cytoplasm and the mitochondrial matrix. Fine calcium precipitates existed in fewer numbers in the intracellular storage sites of spermatogonia and primary spermatocytes, in sharp distinction to secondary spermatocyte and spermatids, which showed an abundance of large and round calcium precipitates, especially in the mitochondrial matrix of spermatids. More calcium deposits were distributed in the plasma membrane (PM), acrosome membrane, and matrices of the acrosome and mitochondria following capacitation; (2) Ca(2+)-ATPase was found in the endoplasmic reticulum system and PM of noncapacitated spermatozoa as well as Sertoli cells. Capacitated spermatozoa showed a weak signal. These results suggest that the presence of calcium in spermatogenic cells might play a role in cell growth and differentiation during spermatogenesis. The Ca(2+)-ATPase function may be inhibited during capacitation, leading to an increase in acrosomal calcium level and triggering of acrosomal exocytosis.